| 摘要 |
PURPOSE: An apparatus for combining a transcoder with an echo canceler of a radio port controller(RPC) in a wideband-wireless local loop(W-WLL) system is provided to increase a switch capacity to reduce a RPC size by combining the transcoder with the echo canceler to implement the transcoder and the echo canceler on one board, to reduce switch load without switching the transcoder and the echo canceler in the RPC. CONSTITUTION: An apparatus for combining a transcoder with an echo canceler of a radio port controller(RPC) in a wideband-wireless local loop(W-WLL) system, comprises a controller(10), a memory(20), an inter processor communication(IPC) block(30), the transcoder(40), the echo canceler(50), and a switch(60). The memory stores programs for controlling operations of each block. The IPC block performs interprocessor communication through a data bus, and detects a modem tone or a fax tone from a pulse code modulation(PCM) signal to report the tone to an upper level. The transcoder is composed of first/second decoders(41,42) and first/second encoders(43,44). The first/the second decoders convert adaptive differential PCM(ADPCM) signals and low delay-code excited linear predictor(LD-CELP) signals of a base station into PCM signals. The first/the second encoders reversely convert PCM signals of an exchange into ADPCM signals or LD-CELP signals. The echo canceler is composed of four echo canceling blocks(51-54) for receiving 32 channels, respectively. The echo canceler cancels an echo signal radiated from a hybrid point interfaced with subscribers in the exchange. Each of a first MUX(61), a second MUX(62), and a third MUX(63) bidirectionally multiplexes a 8.192Mbps signal and a 2.048Mbps signal, the 2.048Mbps signal and a 4.096Mbps signal, and the 4.096Mbps signal and the 8.192Mbps signal, between an outside and the echo canceler, between the echo canceler and the transcoder, and between the transcoder and the outside in the switch.
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